Remember "Pizzagate," the debunked and baseless conspiracy theory alleging that Hillary Clinton was running a child sex ring out of a Washington, D.C. pizzeria? Well, according to a new poll from YouGov, almost half of Donald Trump supporters believe Pizzagate is real. This isn't the first survey showing that large numbers of Trump voters have factually incorrect beliefs about the world, but it's certainly one of the most eye-popping.

To be clear, there was never any evidence that a sex ring was being operated out of Comet Ping Pong, nor that Clinton or any Democrats were involved in a sex ring of any sort. Nevertheless, one North Carolina man who read the rumors decided they were worth investigating and drove over 300 miles to Comet Ping Pong — with an AR-15 assault rifle in hand — to look into them. According the federal charges he's now facing, he fired shots inside the pizza shop once arriving. He found no child sex slaves in the pizzeria.

Here's what's remarkable: Days after his "investigation" of Comet Ping Pong,the man in question told the The New York Times that he still refuses to rule out the possibility that Clinton and her associates were running a child sex ring out of a pizza shop. He acknowledged only that there were no sex slaves "inside that dwelling."

Apparently, a lot of Trump supporters are of a similar mindset. Thursday's YouGov poll, which surveyed 1,376 adults, found that 46 percent of Trump supporters said that the Pizzagate conspiracy was either probably or definitely true.

Unfortunately, this is far from the only falsity that a lot of Trump voters believe. One December survey found that 40 percent of Trump supporters think Trump won the popular vote, when in fact he lost it by almost 3 million ballots. In a different poll, a large majority of Trump voters — 67 percent — insisted that unemployment rose under President Obama. Here in reality, unemployment fell by over 3 percent during Obama's term.

The problem isn't access to information — the facts on all of these matters are easily accessible to anyone who seeks them out. The problem is that a disturbing number of voters — and Trump voters, to be specific — simply aren't bothering to determine what's true and what's not.

Democracy is based on the idea of voters examining the world around them and making decisions about how they'd like to change that world. It's not at all clear how democracy can grapple with a situation wherein a large number of voters are both woefully misinformed about the world and, apparently, opposed to educating themselves about it.